Method of preparing pregnapentaenes

The invention comprises a steroid of the formula wherein R is hydrogen or lower alkanoyl, R1 is hydrogen, methyl, fluoromethyl, difluoromethyl, trifluoromethyl or fluorine, R2 is hydrogen, a -methyl, b -methyl, a -hydroxyl, a -lower alkanoyloxy, R3 is hydrogen or hydroxyl, R4 i hydrogen, hydroxyl, lower alkanoyloxy, halogen or alkylsulphonyloxy and X is and a method of preparing compounds of the formula wherein R1 is H or lower alkanoyl, R2 is H, methyl, fluoromethyl, difluoromethyl, trifluoromethyl or fluorine and represents by contacting a steroid of the formula wherein R2 and -C17-C16- are as defined above and X is chlorine or bromine, with a weak organic base at a temperature of 15 DEG -160 DEG C. and recovering said product therefrom.